Fluorescent tube lighting system



March 2 2, 1949. NATHANSQN 2,465,031

FLUORESCENT TUBE LIGHTING SYSTEM I Original Filed Aug. s, 1946 2 Sheets-Sheet 1 INVENTOR MAX. NATHANSON ATTOR N March 22, 194% NATHANSQN 2,465,031

FLUORESCENT TUBE LIGHTING SYSTEM Original Filed Aug. 8, 1946 Sheets-Sheet 2 CONDENSIVE S!D l N VENTO R MAX.NATHAN SON ATTORNEYS Patented Mar. 22, 1949 UNITED STATES TENT OFFICE Original application August 8, 1946, Serial No.

692,906, new Patent No. 2,436,399, issued February 24, 1948.

Divided-and this application August 23, 1947, Serial No. 770,304

2 Claims.

This invention relates to fluorescent tube lighting systems and the object is to provide improved means for operating a plurality of fluorescent tubes in series with each other at a voltage substantially lower than th sum of the breakdown voltages of the individual tubes.

The present invention is a division of my pending application Serial No. 692,906, filed Au ust 8, 1946, which issued February 24, 1948 as U. S. Patent No. 2,436,399,

Proceeding now to a more detailed description of my invention, reference will be had to the accompanying drawings, in which- Fig. 1 is a diagrammatic elevational view of a transformer and other component elements of a fluorescent tube lighting system embodying my invention.

Fig. 2 is a wiring diagram of the system shown in Fig. 1.

Fig. 3 is a view similar to Fig. 1 but showing a slight modification.

Fig. 4 is a wiring diagram of the system shown in Fig. 3.

Figs. 1 and 2 illustrate a three-tube system wherein inductance coils are used to operate two of the tubes in series on what is hereinafter termed th inductive side of the system.

The transformer generally indicated at 59 in Figs. '1 and 2 is shown as a high leakage reactance shell-type transform r comprising a primary coil 80 and three secondary coils 6|, 62 and 63. The four coils are arranged in side by side relation on a central core leg 64 lying between and paral lel with outer legs 65 and 66, all of said legs being joined to end pieces 61 and 68. Coils 60 and BI are arranged on leg 64 at one side of high leakage reactance magnetic shunts 69. The remaining coils 62 and 63 are arranged on leg 64 at the opposite side of said shunts.

On what may be termed the condensive side of the system shown in Figs. 1 and 2 a fluorescent tube H is connected across coils $0 and 9! in series with a current-limiting condenser 12. In tracing th circuit connections of tube H, as illustrated in Fig. 2, it will be noted that primary coil 60 is connected across an alternating current potential source 13 by leads M and iii. The left hand end of coil 60 is connected at junction 16 to the right hand end of coil 6 I. The left hand end of coil E l is connected to the transformer side of condenser 12 by lead 1?. The tube side of condenser 12 isconnected to the left hand electrode of tube H'by lead it. The right hand electrode of tube H is connected to the right hand end of coil 60 by lead 19. The condenser i2 is charged by the high voltage secondary coil 6! and serves as a current limiting device for the current which is supplied to tube ii to establish an ionized, conductive, and luminescent condition of said tube.

On what may be termed the inductive side of the system shown in Figs. 1 and 2, a pair of fluorescent tubes 8i and 92 are connected in series with each other across the coils 80 and 62 by circuit connections which may be traced as follows:

The left hand end of coil 62 is connected by lead 83 to the left hand end of coil at junction 16. The right hand end of coil 62 is connected by lead 84 to the left hand electrode of tube 82. The right hand electrode of tube 82 is connected to the right hand electrode of tube 8| by lead 85. The left hand electrode of tube 8! is connected to the right hand end of coil 60 by lead 86 joining lead 79 at junction 81.

The left hand end of coil 03 is connected to the right hand end of coil 62 at junction 88. The right hand end of coil 63 is connected to the right hand electrode of tube 8! by lead 89 joining lead 05 at junction 90. t

From the foregoing description of the tube connections on the inductive side of the system shown in Fig. 1 and Fig. 2, it will be apparent that tubes BI and 82 are connected in series across across the coils 60 and 82 by way of series-leads 84, 85, 80 and 19. Coil 63 is a high impedance coil which, when connected as herein described, provides a high-impedance current-limiting bypass through which a limited amount of current is shunted around tube 82 to initially establish an ionized and conductive condition of tube 8!. The impedance of tube 8! is thus reduced to a value at which the voltage drop across said tube is extremely low in comparison with the voltage initially required to establish an ionized and conductive condition of said tube. When an ionized and conductive condition is established in tube 8i by the small amount of ionizing current supplied to this tube by way of by-pass coil 63, the voltag available across coils 6i and 62 is immediately effective to establish an ionized and conductive condition of tube 82 and to cause sufficient current flow through the series connected tubes 82 and 8! to establish and maintain in both of said tubes the current density required for satisfactory operation. In this connection it may be explained that coil 62 is a high inductance coil which serves, in conjunction with the magnetic shunts 69, to limit the operating current in the series connected tubes 82 and 8| to practical design limits.

The system shown in Figs. 3 and 4 is similar to that shown in Figures 1 and 2 with the exception of a modification of the circuit connections of the coils 62 and B3 and the series connected tubes 8| and 82.

Referring more particularly to Fig. 4, it will be noted that the left hand end of coil 62 is connected, by lead 83, to the left hand end of coil 60 at junction 16 and that the left hand end of coil 63 is also connected to lead 83 at junction 9|. The right hand end of coil 62 is connected to the right hand electrode of tube 82 by lead 92. The left hand electrode of tube 82 is connected to the left hand electrode of tube 8| by lead 93. The right hand electrode of tube 8| is connected to the right hand end of coil 60 by lead 94 which joins lead 19 at junction 81. The right hand end of coil 63 is connected to the left hand electrode of tube 8! by lead 95 which joins lead 93 at junction 95.

In the system shown in Figs. 3 and 4, a high voltage is impressed on tube 8| through coil 63 which is wound directly on coil 62 and suificient bleeder current flows through coil 63 to establish an ionized and conductive condition of tube 8|. When tube 8| is ignited, the reactance of coil 63 limits the current in said tube to a value just sufficient to maintain ionization and current flow. The resulting drop in the impedance of tube 8| enables the voltage generated in coil 6'2 to establish an ionized and conductive condition in tube 82 and to cause sufficient current flow through both of the series connected tubes 82 and BI to establish and maintain in both of said tubes the current density required for satisfactory operation. The coils 62 and 63 shown in Figs. 3 and 4 are designed so that they are effective, in conjunction with shunts 59, to limit the operating current in tubes 82 and 8| to the proper value.

Both of the systems described herein provide feasible arrangements for effecting instantaneous starting and operation of series-connected fluorescent tubes without employing operating voltages in excess of the sum of the break-down voltages of the individual tubes.

Having thus described the nature of my inventionand several embodiments thereof, it will be understood that various modifications may be resorted to within the scope and spirit of the invention as defined by the appended claims.

What I claim is:

1. In a fluorescent tube lighting system, a transformer including a central core leg and two outer core legs joined by end pieces, a primary and two secondary coils connected together in auto-transformer relationship and arranged in side by side relationship on the central core leg with the primary coil lying between the secondary coils, and magnetic core shunts of high reluctance separating the primary coil and one of said secondary coils, two fluorescent tubes connected in series with each other across the primary coil and the last mentioned secondary coil, means, including a high impedance coil directly connected to said last mentioned secondary coil and to the connection between. the two tubes, affording a current-limiting by-pass through which a relatively small amount of current is by-passed around one of saidseriesconnected tubes to establish an ionized and conductive condition of the remaining series-connected tube and thereby enable both of said tubes to be operated in series at a voltage substantially lower than would be required in the absence of said by-pass means, and an additional tube connected across the primary coil and the other secondary coil in series with a current-limiting condenser.

2. A fluorescent tube lighting system as set forth in claim 1 in which said high impedance coil is wound directly on the secondary coil serving said series-connected tubes.

MAX NATHANSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,358,810 Karash Sept. 26, 1944 2,370,635 Bridges Mar. 6, 1945 2,429,162 Keiser Oct. 14, 1947 2,436,399 Nathanson Feb. 24, 1948 

